gitignore: allow .pylintrc to be tracked

The .pylintrc file was introduced by commit 02df8e3b333c ("docs: add a
.pylintrc file with sys path for docs scripts") to provide Python path
configuration for documentation scripts. However, the generic ".*" rule
in .gitignore causes this tracked file to be ignored, leading to warnings
during kernel builds.

Add !.pylintrc to the exception list to explicitly allow this
configuration file to be tracked by git, consistent with other
development tool configuration files like .clang-format and .rustfmt.toml.

This resolves the build warning:
.pylintrc: warning: ignored by one of the .gitignore files

Fixes: 02df8e3b333c ("docs: add a .pylintrc file with sys path for docs scripts")
Signed-off-by: WangYuli <wangyuli@uniontech.com>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/1A357750FF71847E+20250623071933.311947-1-wangyuli@uniontech.com